The long range goal of this research is to study interphase chromosomes in the form of prematurely condensed chromosomes (PCC) which are induced in interphase cells by fusion with mitotic cells, and ultimately relate the composition to genetic inheritance and the process of oncogenesis. We are able to take advantage of the cell's ability to subdivide and partition its genome along with the proteins present at the time of condensation by persuading the cell to prematurely organize its chromosomes. This is a unique system in that morphological and biochemical questions which are unapproachable by any other method may be answered. To pursue the above stated goal, I shall isolate and purify PCC from sequential stages in the cell cycle, correlate morphological and ultrastructural relationships of the PCC throughout the cell cycle, gain insights into biochemically analyzed isolated PCC to determine nonhistone proteins which have a transient involvement with the interphase chromosome, determine the protein(s) which are responsible for chromosome condensation, and localize specific nonhistone proteins of interest on PCC and metaphase chromosomes.